YIPEE! 18.4 BELOW Zero Outside, 31.6 In!

Challenges of the Solar Greenhouse by Jack

It’s the dead of winter here. No – it’s not like, say, Minnesota, where I spent some time in that un-holy frigid icebox. But the 6500 foot elevation of our high desert plateau is still no tropical island paradise. Last week when the snowstorm gripped the whole of the US and the jet stream dipped into Mexico and swooped across the southern states as well – we got slammed. I thought our rows of bok choi, chard and mizuna were goners.

On the coldest night, the temp slid all the way down to 18.4 degrees BELOW zero Fahrenheit (only 6 degrees short of a century-record low!). The greenhouse is almost 2000 square feet – so we’re talkin’ a pretty big space with only plastic for sides to keep warm. But by morning, when the sunshine happily broke over the far mesa and immediately started relieving the chill inside (it was still 14 below outside till noon), the greenhouse stayed just the tiniest nick under 32 degrees – 31.6.

No big deal, you say? Well YES it is! You see, we’re running a “solar” greenhouse, not a fossil-fuel guzzling heated greenhouse where ya just set the thermostat and close the door (and listen to the dollars wizzing up in smoke…).

This is a solar greenhouse that collects the majority of it’s thermal season-extension heat in over 50,000 pounds (6000+ gallons)  of water inside that gets warm during the day and stays warm into the night, releasing slowly the stored sunshine energy as the dark night crawls towards dawn. Now because you cannot possibly compensate for such a frigid night with only thermal mass, I knocked together a 55 gallon drum wood stove last year with galvanized zig-zag pipes circulating water over the stove and through the soil. The stove itself kicks out over 100,000 btu’s and that is what saves our plants little green butts on nights like that.

What we find is that on a any night over 10 degrees where the sun has been out most of the day, the greenhouse stays somewhere in the 30’s – no problem for the tender greens as the soil temp is between 45 and 60 degrees throughout the greenhouse. But when the arctic front dips low and catches us in it’s wake, we fire up the wood stove in the afternoon and at 10pm, stuff it with 4-6 of the biggest logs that will fit in the stove door. Then we trudge (this time through over a foot of drifted snow) up the hill home and try to forget it and sleep.

It’s a funny game – playing with the “momentum” of heat gain and heat loss. As I write this, tonight is going to be somewhere in the 10 degree range – but we had a very sunny day, so I may take my chances and not go and start a fire in the wood stove …

… then again, I might!

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Do you have any experiences with growing through the winter with a greenhouse (or without)? Please share it here!


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5 Responses to YIPEE! 18.4 BELOW Zero Outside, 31.6 In!

  1. James says:

    Wow those pictures are awesome! I would love to hear more about your solar power system and other stuff you’ve got that keeps you off the grid 🙂

    • daiajack says:

      thanks James – we’re doing the off-grid stuff bit by bit – you can find stuff about our solar cooker, solar hot water and solar greenhouse and some solar thermal storage work to keep a few more rooms warm in our houses so far – we’ll talk too about the electrical system and then the water collection at some point soon – c’mon back–

  2. Fascinating! Your green house is HUGE! You must be doing this commercially? I’m assuming you’ve read Eliot Coleman’s books Winter Harvest and Four Season Gardening. He’s in Maine and uses a second cover over his plants on cold nights. You have a lot to cover, but then again, so does Eliot. A second cover directly over the plants (frost blanket) could keep the temp underneath up by just a few degrees – perhaps enough to save the day??

    I’m wanting to erect a hoop house this year myself, but still trying to decide on the best materials and structure to handle snow load. Your system looks much more permanent than what I plan to do, but if you have any tips, I’d love to hear them.

    Thanks for linking up to the Barn Hop!

    • daiaravi says:

      Well – yes – although it is big, when you look at what a family/community needs to have in cultivation to support them – about 1 acre – then 2000 square feet is not that much (1 single bay of a “commercial” greenhouse is actually 3000 square feet…) that said – we are hoping that – if successful enough – we can take our extra produce to market – at least that’s the idea at this point – we have a few hurdles to over come –

      and yes – elliot is an inspiration! a 2×4 structure worked for us – but we are in a dry climate and the wood will (hopefully) not rot very fast – you know – mother nature wants it all back! I can only encourage you to do some thermal mass like many water-filled water jugs painted black – the impact of that is substantial! (and the more the better…)

      thanks for the visit!

  3. Love your pictures of your greenhouse space – so great that you are managing to keep it warm enough throughout the winter! Looking forward to reading more.

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